Alternatively, one may analyze it as a hadronic molecule, i.e., as a bound
state of conventional \(D\)  and \(K\)  mesons. Mesons \(D^{-}\)  and \(K^{+}\)  may
form a bound state if the mass of a molecule \(D^{-}K^{+}\)  is less than
corresponding two-meson threshold \(2365~\mathrm {MeV}\) . But this estimate is
considerably below the mass of \(X_{0}\) , therefore, it is difficult to expect
that the molecule \(D^{-}K^{+}\)  can be considered as the \(X_{0}\)  state. For
compounds \(\overline{D}^{\ast 0}K^{\ast 0}\)  (hereafter \(\overline{D}^{\ast }K^{\ast }\) ) and \(D^{\ast -}K^{\ast +}\)  relevant two-particle thresholds are
equal to \(\sim 2900~\mathrm {MeV}\) , and hence they cannot dissociate to
vector mesons \(D^{\ast }\)  and \(K^{\ast }\)  provided masses of these molecules
are below this limit: An estimation for the mass \(2848~\mathrm {MeV}\)  of the
scalar molecule \(D^{\ast }\overline{K}^{\ast }\)  obtained in Ref. [1]} supports this assumption. But such hadronic molecules can
decay to a pair of pseudoscalar \(D\)  and \(K\)  mesons. Then, structures \(\overline{D}^{\ast }K^{\ast }\)  and \(D^{\ast -}K^{\ast +}\)  may be interpreted
as \(X_{0}\)  if their masses are compatible with \(m_{0}\) . The scenario with \(D^{\ast -}K^{\ast +}\)  as \(X_{0}\)  was realized in Ref. [2]},
in which the authors calculated the mass of the molecule \(D^{\ast -}K^{\ast +}\)  in the framework of the QCD sum rule method. Result obtained there \(2.87_{-0.14}^{+0.19}~\mathrm {GeV}\)  indicates that an assumption about
molecule structure of \(X_{0}\)  deserves detailed studies.
